A vehicle fuel emissions system may include multiple components, such as valves, disposed inside a fuel tank and vented outside the tank through corresponding apertures through the fuel tank. The fuel tank may also include additional apertures corresponding to, for example, fuel lines, purge nipples, ports, and other system components.
To minimize emissions, the system should have a low level of permeability to both liquid fuel and fuel vapor. Each opening, or “penetration,” formed in the fuel tank to accommodate the apertures also creates a permeation path, and the permeability of the fuel tank increases as the number of permeation paths increase. Thus, it is desirable to reduce the number of fuel tank penetrations, especially in view of the particularly strict emissions requirements for Partial Zero Emissions Vehicles (PZEV) and Ultra Low Emissions Vehicles (ULEV). On the other hand, there still needs to be a sufficient number of fuel tank penetrations to accommodate all of the apertures needed to link the fuel tank with the other components in the emissions system.
There is a desire for an arrangement that can provide multiple apertures to accommodate multiple components in the fuel system without increasing the permeability of the fuel tank.